21-05-2003 13:49

DougHogg

I was admiring the above picture of the TechnoKat Transmission 2003.

Can someone explain the light blue inserts in the green and dark-blue gears?

Also I gather that the purple and white pieces are bearings. Is there a reason for them being different colors?

Lastly, I gather that the orange piece connects either the green or dark-blue gear to the red shaft. Is that correct and if so, how does it connect to the red shaft?

21-05-2003 14:11

Bill Gold

The engaging system looks like their 2002 transmission. The engager is on a hex shaft and the gears on bearings or just freely rotating until the engager locks into the side of either gear.

21-05-2003 14:46

Andy Baker

Doug,

Thanks for the interest. Bill has it right, but I will be more specific.

This design idea came from Steve Butler, an engineer on our team who was into racing. I made the detailed design, using his idea, and put it on our 2002 robot. This is a more refined version, put on our 2003 robot. Clark and Kyle Gilbert made this model in Inventor and created this nice "cut away" view.

The aqua colored parts that fit inside the gears (green and blue gears) are 3/8" id flange bearings. The gears freely spin on the red shaft and transfer the torque to the red shaft via the orange "dog" gear.

The purple and white bearings are the same as the aqua bearings (3/8" id flange ball bearings). They were just shown in different colors for clarity purposes, I believe (the Gilberts' idea).

I must say that these gearboxes really performed well for us this year. We had some drivetrain problems, but none were due to this gearbox (other gears and belts outside of this gearbox were more problematic).

My plan is to do an extensive white paper on this improved design and release it by mid-June. Next year, we'll probably use this design again, with more improvements.

Andy B.

22-05-2003 04:49

DougHogg

Thanks Bill and Andy for clearing up my confusions. I will also take a look at the white paper from last year.

I know that a number of teams used a version of the 2002 TechnoKat Transmission this year:

226, 368, 968... Anybody else?

Anybody have tips for people new to gear box design/building on making one of these? Any problems you ran into and their solutions?

22-05-2003 15:29

Matt Reiland

I love the tranny, it worked perfectly for us this year, it had ample power for whatever we needed it to do. This gearbox would allow our robot to literally wheelie off the line, and almost completely jump the plastic on the ramp. All this with blue supergrip belts!

Tips/Tricks you ask:
1. We switched all gears to standard martin 20 pitch. Low was an 80:20 tooth high was 50:50
2. We made a gear that was 16tooth and welded on a 48 tooth 0.7 onto it and pressed it onto the CIM for the first stage, the ratio worked well matching the CIM to the Drill. The end of the 0.7 mode gear was then turned down to fit in the bearing on the opposite side of the CIM motor. Now, this assembly was too large to be removed from the motor plate after the gear was pressed on, next year I suggest making the CIM motor mount removable keeping the gear intact.
3. MAKE SURE THAT THE CENTER DOG CAN NOT BE IN HIGH AND LOW AT THE SAME TIME. We had one gearbox slightly narrow and the box went from full speed to no speed instantly, ripping the pinion off the drill and severely bending some teeth on the 0.7 mod mating gear.
4. Harden the dogs and dog mate (In fact do like the picture shows and get rid of the dog mates, mill them into the gears) We ended up welding the dog mates onto the gears after shearing off the three screws that held each on.
5. We omitted the carrier for the end of the drill motor, it was only supported on the motor can side.
6. Lighten up all the gears lots, the box is heavy otherwise
7. Air shifting worked fine, we are investigating using RC Servos for next year.
8. Suggest using gear drive out of the gearbox, we were throwing chains at Buckeye until we made automatic chain guides for Buckeye.
9. Suggest that everyone put a 90 degree break on the top and bottom of the gearbox plates for strength, ours are pretty warped after the season (But they still keep kicking)

If I think of more I will post.

19-06-2003 17:01

dddriveman

Can anybody say "Built by engineers". This kinda stuff realy makes me angry. When your engineers build your componets for your robot it is a disgrace to what FIRST is about. THe point of First is to see what the students can create not what their engineers can create, then school them on. Just in case asked a question about it by a judge or inspector. I can't even count how many teams I have seen at regionals where you could have watched them work all day long in the pit on their robot and the never once saw a student touch the thing. Some stuff needs to be changed. It's just not fair to other teams. Us one of them, we don't have any big fancy engineers helping us or building our robot. DO you know how many engineers we have? How about this number. ZERO. All those teams out there were your engineers do the work and not you, should feel real bad about yourselves,and any awards you have won. 'cause you didn't build your robot your engineers did. You know what the great thing about our team is it. We built our own robot, and at the end of the match we can hold our heads up high regarless of the score because, WE built our OWN robot.

19-06-2003 17:16

Madison

Okay, you're new here, so I think we can manage to cut you a few inches of slack.

We have discussed this again and again and again .

The TechnoKats have proven themselves to be one of the best teams in FIRST, not only because of their consistently well-designed and -performing robots, but because of their outstanding team members and the immense help they provide to our community.

While it may appear to you that this transmission was designed entirely by engineers, please keep in mind that they shared it with everyone -- including teams like yours that don't yet have the benefit of engineers to guide them.

Furthermore, I and several others are working toward bringing engineering resources to your team and teams like it through a new initiative. We're all trying to help one another here, so let's hasten the righteousness a bit, okay?

Okay.

19-06-2003 17:30

Rob Colatutto

Hmm... For starters M is right about the TechnoKats being one of the best teams around and a number of thier transmissions are up in the white papers with detailed drawings so anyone who wanted to make one could. If you go and ask anyone on team 45 how thier tranny works, they'll be able to tell you what you wanted to know and then some more. Its not like and engineer is sitting over there designing amazing parts for thier robot without getting students involved and making sure everyone understands whats they are making. If you just listen and look around at some old posts you can learn a lot from this team, and from the engineers involved with FIRST.

19-06-2003 17:36

Andy Baker

(I was going to go easy on this issue, but the above author has been reading this website since the first part of this year, so...)

Sometimes I think a while before posting, sometimes I go with my gut and shoot from the hip. This time, I'm going with my gut. Enjoy. It doesn't happen very often.

dddriveman is right... some stuff needs to be changed. However, I disagree with the assesment above. Attitudes need to change. The attitude that promotes attacking other teams and people needs to go away right now. This attitude is being shown by dddriveman above and by others on these valuable forums. This sort of attitude is driving good people (students and adults) away from these forums and I am simply not going to stand back and let it happen.

dddriveman, it is unfortuneate that FIRST means something different to you than it does to almost everyone else out here in FIRST world. I suggest that you look into another robot competition if all you care about is promoting yourself and knocking down others. I cannot let this sort of crap go on.

As for engineer/student involvement and this thread involving the TechnoKat gearbox... you have no clue. You cannot sit there and tell me that 12 years of doing FIRST, working with hundreds of kids is something I "should feel real bad about". Ask Jadon Smith, a former TechnoKat student who had no where to fit into Kokomo High School 8 years ago, but recently graduated from MIT and works for a place that he cannot tell me about. Ask Phil Lundberg if I should feel bad about helping him become a leader on team 45, inventing CVTs and designing transmissions for Saturn VUEs at the age or 19. Ask me about Chris O'Neill... who quit team 45 as a Junior because things got kinda tough, but now he is an engineering student at Purdue. (this is only the beginning, I can go on and on and on with examples of student success stories)

Go ahead and set up a poll on this website, asking other students who are drivers and student team leaders and ask them if I should be ashamed of myself. I dare you. My guess is that your attitude will back down.

As you can tell, I feel strongly about this issue. FIRST is about Inspiration, simply put. It is great to see students do things without engineering assistance, but FIRST is not about seeing what students can do on their own. Go enter a science fair if you want to show what you can do... but if you think that you can drive us engineers away from FIRST by berating us and telling us that we should be ashamed of our actions, you must be joking.

So, yes... things need to change. Attitudes need to change. I know that I am being harsh with this note, but it is about time that someone stepped up.

Andy B.

/edit - M. & Rob... I appreciate both of your comments... they mean alot to me. Heck, Rob and I have even debated this issue before, but he was tactful and respectful while having a different opinion. Having a different opinion is OK with me... attacking me ticks me off. And you wouldn't like me when I'm angry.

19-06-2003 18:01

Amanda Morrison

Team 45 is one of the best teams I have ever competed with, hands down. They are gracious to other teams, they compete in a professional manner, and most of all, their kids really LEARN. Their students are excited about the program and the changes that they can make in FIRST. They are informed, intelligent, and some of the friendliest kids I've ever met. Their mentors are dedicated people who work constantly to improve FIRST and their own community. Indiana is a better state for having such a great team.

My small team needed some help after we had built 4 drive trains and had just about given up hope. Mentors from Team 45 came over and gave my kids a couple ideas as to how to get our machine up and running again, but let the kids learn and experience just how to make it work. I have utmost respect for their team and the way they operate.

I'm sorry that you have the feelings that you do. I hope that you get to experience the TechnoKats in competition and bear witness to their friendly demeanor sometime soon.

19-06-2003 19:13

Ken Leung

I've made a post for a topic exactly like this, so... I am just going to copy and paste.

-----------------------------------------------------------------------------

I totally understand those of you who feel frustrated watching those cool looking robots win the competition... I once was on a team who mostly used bandsaw and drill press to build a robot out of students' hands. And I felt really jealous when other teams have gear boxes while we could barely host clamp the drill motors on a piece of ply wood.

But I grew out of those feelings as years past because, as years pasted, my team (as well as others) did great at competition even without great engineering support, or fancy machining... As a team, we were able to build better robots just by more and more experience, harder effort in fund raising, and getting help from different people.

I grew out of those feelings as I see other teams won competitions without great engineering. Team 254 cheesy poofs is a classic example, as well as my old team 192, and many other teams. Great gear boxes and complicated machines were only few of the many factors that decide how your robot will do in a competition. There are also scouting, strategizing, and communication between driver and coaches, or between you and your alliance partner.


What is the unfairness between teams anyway? Well, we were all given the same kit of parts, the same battery, and the same rules. Everyone have the same weight and material limit, as well as how much motors/pneumatics we can use. The differences between the teams are their experiences and resources...

With more experience, a team can build a much better robot... Can you really call that unfair? With more resources teams found, they can build a better robot... But who's stopping you from going out to find more resources? Can we really say it's unfair because our area happens to have less resource for us to use?


A lot of well-supported teams are really cool teams if you get to know them. They've always done great at regionals, and their robots were always really effective and simple. Their team is high spirited, and was great help to teams around them. So, I really do believe they are all great teams to learn a lot from. Take your time and get to know their whole team. That's what competition is for.

Mean while, I challenge you all to build your team to as good as theirs. Go out and get engineers interested in this program. Go out and get more sponsors to help out.

Also, I've seen a lot of their robots, and most of you could build robots just like theirs without great machining (although yours won't look as good). They have a lot of simple original ideas what work quite well at the competition, and it's not hard to build.

Don't feel so frustrated... You have plenty of chances to improve yourself, and make your robot better. You can be competitive in a competition if you keep building a robot that you are proud of.

Mean while, keep sharing your ideas and take advantage of this forum. A lot of other people and I are willing to share what we learned, so don't be afraid to ask.

-------------------------------------------------------

A little I want to add. Having NO engineer support is NOT an excuse for you to and say "oh such and such teams have 10 engineers building the robot for them. I am not even going to try anymore." It is YOUR JOB to get more engineers involved in your team, so you can work TOGETHER with those engineers, and learn from them. It doesn't mean you tell the engineers to build the robot for you. It means you ask for help and guidance and support when you need them, and make use of their knownledge as much as possible.

When you face a difficult challenge, you don't look at the answer. You ask for help, and try to learn enough to solve the problem

There are plenty of people around here who are willing to offer their advices. So make use of this forum, and learn as much as you can so you can build those good looking robots too.

19-06-2003 19:21

dddriveman

I'm sorry about my last statement. I did not mean to attack or single out in any way, shape, or form the Technokats. I was trying to get the point across that some stuff needs to be changed. Again I am not singling out team 45 or any other FIRST robotics team. I also did not mean to come across that strong and I hope that my actions have not impared anyone elses judgement of team 979. I am sorry once again. I also know that the Technokats are a wonderfull team and experienced, as from experience at last years Buckeye Regional.

19-06-2003 19:48

Gadget470

Since it seems you've spotted your own err, i'll go easy

The technokats are a very inspirational team. They inspire their engineers, their students, and other teams. Many teams have had a good season because of the Technokat's generosity.

For example, team 909 (i think) was able to compete at a regional with a robot that was prototyped, designed, constructed, and loaned by the Technokats. Now, I say the team name because it wasn't just their engineers. It wasn't just their students. It was their team. Their students working directly with their engineers.

I, for one, am against "Engineer Built" robots. My reasons are posted in other threads. It's a much different story with "Engineer Assisted" robots, and I even envy the "Student Built" robots.

I was on a team in my home town for 3 years. I joined as a freshman, loved the program, even though the robot sucked and it was mostly engineer designed and built. Second year? About a week after we got the game, we went to the sponsor's building, and were shown cad drawings of what was going to be built. Again, engineer designed, performed.. better. But, at this point I was exposed to two things: 1) The awesome power of CAD, 2) How engineers think. Onto my 3rd year, again, mostly engineer designed.. but me and my dad saw a major flaw in a major part of the robot. After a redesign, we ended having our best year yet.

This year I was on a different team, one that is 40 miles away from where I live, (that's about an 45 min to an hour by car). I made the drive almost every day. The robot is mostly student built (more than 85% designed and built by students), but also had engineers who wanted to "Make you guys the best $@#$@#$@#$@# engineers you can be."

We were taught through the season engineering practices, and building methods. If something wasn't working right, an engineer would take a look at it, and modify it's design. This was my best season ever.

Now here's the reason you read all of that (assuming you did)...

I would have ZERO drive to join team 470 if it weren't for team 247. The engineer built robots made me want to be the builder. I got my chance every day, after driving through the lovely Michigan winter weather.

Now I've graduated high school, while most kids take that first Monday after school's out and sleep until noon then go out and party. I started my job. Where do I work? Comau Pico Powertrain Systems, in the engineering department. (Oddly enough, Comau Pico is one of 247's sponsors ).

So honestly, if the team is inspired, then so be it. An engineer built robot doesn't always perform better than the student built ones. Inspire your students, then build a robot as you all see fit.

Technokats have done this tremendously. The way they build is to let everyone be inspired once their students are.

19-06-2003 22:50

Andy Baker

Accepted

driveman,

Apology accepted. Actually, I understand your frustration and see it often in FIRST. I am frequently frustrated when I see engineers/adults only working on a robot and students standing around watching. This happens in my team's pit sometimes, and I try very hard to make it not so.

Some of my most enjoyable times in FIRST have been when team 45 students "kick out" the adults from the pits... that makes me very happy and does not happen enough.

The way I see things is this: there is a fine line between student involvement and engineer involvement. Students and engineers should work side by side, actually inspiring each other. I can attest that many students on team 45 and on these forums have inspired me. This inspiration happens both ways.

Please keep your eyes open and try to understand that there are vast benefits to working with excellent engineers like Raul Olivera (111), Paul Copioli (217), Mark Jones (343) and Glenn Thuroughmann (60), just to name a few. There are a slew more, believe me. Take a chance and get to know these guys, and the other dedicated engineers in FIRST. Not only will you learn from their wisdom and experience, but you may also find a friend.

Other smart FIRST students have also had the same opinion you have... now, they may have shown it with more tact, but you may want to talk to them also. Please take the time and talk to other students in your position and learn from their experience.

No harm done.

Andy B.

20-06-2003 10:19

Andrew

FIRST's goal is to inspire people to pursue careers in science and engineering.


It's mechanism is to create an environment in which Engineers are recognized as role models.

FIRST creates an avenue where young people are exposed to Engineers in daily life. If you think about it, there are no TV programs glorifying the world of engineering. There are very few outreach activities which put engineers directly into contact with the community.

So, if you take the Engineers out of FIRST, what do you have left?

Although Engineers are extremely competitive, we all need to realize that FIRST is -not- about winning the competition. The only reason to have the reaction "Those lousy engineers out-designed me" is because you are too focussed on winning.

The best part of the competition (for me) is to go around the pits on practice day (usually after the crowds have left) and check out all the great designs that people have put together.

Some of the most talented people in the world are designing robots in FIRST. If that were taken away, all of us would be poorer for it.

20-06-2003 16:10

Gadget470

Perhaps your post would have been fitting elsewhere. But you picked out one of the most (if not the most) respected teams in FIRST.

I see you are sincere in your regression, and I'll back down now too. The issue here is now dead, please, if you want to start a debate, or continue a debate of the subject.. find the approprioate sub-forum and/or thread.

Smiles

20-06-2003 19:09

dddriveman

The issue is now dead, and I wish that I never brought it up it was a stupid comment that was very immature and unprofesional of me to say what I did.

22-06-2003 09:01

Joe Clohessy

NO dddriveman, your right. My team 522 has 0 engineers. But ya know what feels good.? When you get against a team with 5 million to spend and engineers build their bots and you win. Yes I agree with what some people were saying, if you go to any of the Delphi teams they will know the robot in and out, there drilled and tested and told what to say to a judge, what to do and when to do it. As some of the TEAMS not the engineers it feels great to show them down. Knowing that an engineers 100 hrs + of work just didn't make it through your 10 hrs of work. Sometimes its not all equations its just trial and error and common sense.

22-06-2003 10:20

Gadget470

Joe.. please see my post.. with the following:

So.. you represent your team and say now that it's more important to win against an Engineer Built team than to learn from them. By pointing out your team number, you are calling yourself the opinionator of the team.
Honestly though, I think if your team had the opportunity to have engineers, you wouldn't turn them down.

As I said before:

22-06-2003 12:00

Brandon Martus

It's not fair to close this thread, because people may actually want to talk about 45's transmission in the future. So, I am asking that any more 'engineer built' comments be put into their own thread, preferably one that already exists. Yeah, I'm asking you to go do some research before posting. I know it sounds hard and you've got stuff you just have to say, but you may learn something. You may also see that the exact words you are going to write have actually been posted 10 times before, argued to death, and everybody agreed to disagree.

Thanks.

22-06-2003 15:24

generalbrando

I have a quick post about the transmission. I've seen it up close at the Indiana FIRST workshop and talked with team members about it (a student explained it to me). When I first saw the video showing the robot changing gears in motion I was quite amazed. I couldn't imagine how to design something to do that so effectively and as it turned out, the solution was simple, reliable, and cool. Nice job. If only we could build 'em like that .

P.S. Thanks for always sharing your designs!

22-06-2003 21:06

Matt Reiland

Generalbrando,

Don't sell yourself short, you can build them just like that. We took the design and modified it to use off the shelf gears from Martin Gears. The only parts that took time to machine were the hex driveshaft and dog/mates. These could be easily farmed out to a local machineshop as we did for a very, very low fee when the shop was told what they were for. The tranny has proved to be robust, and reliable. The 2003 modifications make it even smaller and lighter. There are also some other designs in the white pages for shifters

22-06-2003 22:45

generalbrando

LOL

Sorry to give the impression that we just couldn't duplicate their designs. It was actually a joke. During competition we redesigned our drive train over 7 times (no joke), putting us on the field with a new attempt each and every time. Note to self and all listening: never use bicycle sprockets! It wasn't my idea and there's no need to point fingers, so I'll leave it at that.

As for creating something like this drive train for our robot, we didn't have the tools or money needed, not to mention the fact that we decided not to use gears (next year may be very different). I know that seems odd, but the reason is simply that we couldn't contruct something that we were confident enough in to think it wouldn't get twisted and mess up the gears or gear boxes. We had trouble keeping our sprockets in relative alignment .

Anyway, thanks for your tip on getting something like this made cheap and easy.

22-06-2003 22:50

sanddrag

How low of a fee was it? Any numbers? We usually do our own machining so I have no idea how much anything like that would cost.

23-06-2003 03:14

DougHogg

Matt,

We had trouble with "throwing chains" also. Can you elaborate on your automatic chain guides?

23-06-2003 15:13

Matt Reiland

Doug,

I will get a picture but what we did after Buckeye was take off the sprockets and make some delrin (Actually it was my kitchen cutting board, some kind of plastic) rings that were bolted to each side of the sprocket, they had a steep chamfer at the top that pretty much forced the chain to ride back into the teeth on the sprocket. Unless the chain broke there was no way possible for the chain to derail. Worked perfectly for GLR (We Won!) and at Nationals. This proved to be the most reliable and easy solution to using chains yet. Even better than a tensioner.

23-06-2003 15:15

Matt Reiland

The fees for the parts jobbed out were on the order of $40 per dog mates, and about $80 for the main dog or hex drive shaft. These are on the cheap side, but like I said make it clear to the shop what they are for, especially if they are light on work

23-06-2003 15:37

sanddrag

Matt,
What size chain did you use? I know 980 used #25. We used #35 with a four motor drive with less than perfect alignment. We threw a chain only once when we rammed a wall at full speed. (Oops! )

Our sprockets and chains took up a lot of weight this year. Would it be worthwhile downsizing to #25?

23-06-2003 16:01

Matt Reiland

Sanddrag, we used the smaller #25. We never had any problems as far as strength, only throwing the chains. I wouldn't use #35 for drive anymore, #25 was adequate and we had a ton of power this year in low gear with tank treads. By using the chain guides there were no drawbacks to #25 chains

23-06-2003 17:58

DougHogg

Very cool. Thank you.

We are working on improving our chain drive before IRI. I will pass the idea to our team.

24-06-2003 23:21

Gadget470

After Buckeye? *cough* illegal *cough*... oh well. Good job guys. (poking some fun)

25-06-2003 03:36

Cory

Umm no, it wasnt illegal. You were given till Wednesday after each regional you competed in to make any brand new parts that *werent* identical to ones on your bot during the competition (I think it was Wednesday, but whatever. You had a few days to make stuff)
[edit] After Buckeye only implies that it wasnt done at a competition
Cory

25-06-2003 07:52

Matt Reiland

Gadget:

From the final Team UpdateARTS FABRICATION AFTER EVENTS
In order to better allow teams to replace robot components that fail or do not work well at
competition events, FIRST will adopt the following:
1. At the competition events, teams can build whatever they want:
• Spare parts;
• Replacement parts;
• Extra parts;
They must be fabricated on-site utilizing available fabrication resources. We are,
however, concerned about the potential for teams to over-utilize the competition machine
shop in the fabrication of new parts when the shop should be dedicated to repairing parts
required to keep robots running and able to participate. Therefore, a machine shop’s top
priority will be repairing parts with fabrication as time allows
2. After each event in which a team participates, the team has until midnight Wednesday
(local time) immediately following their event to repair and/or fabricate new
mechanisms and may bring these parts and mechanisms to any subsequent events. As
before, we must rely on the gracious professionalism of teams to adhere to the rules of
the FIRST Robotics Competition.

As for a picture of the guides: These were made immediately after the event in my basement on my own lathe out of my kitchen cutting board!!

25-06-2003 09:46

Andrew

I thought they said that berylium, titanium, and Kitchen cutting board were not allowable!

25-06-2003 19:47

Gadget470

I retract my statement and shall promptly face the corner.

26-06-2003 12:30

Tytus Gerrish

Evrything fits togeather But How is it asembled? Im shure after staring at it for a while ill get it But could someone save me some time please

26-06-2003 12:53

Matt Reiland

First, you will take the flanged bearings (Teal Colored) and press them into the output stage gears (Green & Blue)(Ones that interface to the 3-finger Dog (Orange). Next, slide the shift shaft (Yellow) into the hole in the Hex Drive Shaft (Red). Next slide the three finger dog onto the hex shaft and pin it to the shift shaft.(Pin Shown also in Orange) Now slide the 2 output stage gears onto the hex shaft. Next put on the other 2 flange bearings (White & Purple) Onto the Hex Output Shaft (Red) Next weld the second stage onto the shaft (Shown in Silver above right to the output stage). Lastly press/weld the first stage onto the CIM motor.(Hard to see in the pic) Mount all three on one of the gearbox sideplates, add in the cross members, and attach the other gearbox side and POOOF you have a shifting gearbox.

Note: This is the extremely simplified instructions but assembling the box is pretty easy, making it is more difficult.

26-06-2003 13:14

sanddrag

Are there one or two bearings in each output stage gear?

26-06-2003 13:23

Matt Reiland

There used to be two on the Design from 2002, there is only one shown on this newer smaller version for 2003

26-06-2003 14:16

sanddrag

Does it work okay with just one? Well, I suppose it does from what I read about the transmission's success. But wouldn't the gear wobble some on the shaft with only one bearing in there?

EDIT: One more question, what would be the pros and cons of machining the dog mates right into the hub of the gear as opposed to using a hubless gear and machining separate dog mates? I'm just thinking about less complexity.

26-06-2003 14:36

Matt Reiland

The flanged bearings used are pretty beefy, they are about 1/4" thick so as long as your machining tolerances are good, there should be no wobble. You also want your tolerance very close on the bore of the output gears so that they dont' fall off the flanged bearings when they aren't engaged to the dog.

As for machining the dog mates into the gear, it is the way to go, we used separate dog mates and ended up welding them onto the hubless gears. Keep in mind that by machining them into the gears, the gearbox gets much narrower than if the dog mates protruded outwards. The dog mates themselves seemed more complex to machine than actually milling in simple pockets on a rotary table of a milling machine also.

26-06-2003 18:20

KyleGilbert45

wow..me thinks we should hire Matt for the team he seems to know more about the transmission then most the people on our team....

I can contest that even though the manufacturing of the box may not be the easiest in the world for teams the assembly of it is quite easy. I assembled and de-assembled ours multiple times. Buy the end of the season we had the assembly of the gearbox to around 30 minutes each. I haven't talked to Andy about the gearbox since ohhh the last day of nationals but i would think there would be a white-paper for it in the near future. (this is just pure speculation, not confirmed.)

26-06-2003 18:51

I know there were several dozen man hours put in to assemble the parts at the school..so yes it was rather time consuming. Kyle is exactly right, the assembly was rather easy. I assembled 2 spares this year (early in the build when the mechanical team fell behind otherwise I wouldn't be touching that stuff until after its already completed... ) in almost no time at all.

26-06-2003 19:24

sanddrag

I think Matt knows so much about it beacause he has one of his own, or team 226 or whatever. http://www.chiefdelphi.com/forums/sh...277#post163277

26-06-2003 22:11

Matt Reiland

You are correct sir, I love the design.

26-06-2003 23:42

sanddrag

Ratio Change

A few months ago I was doing some numbers on this drivetrain and found that a 60:40 ratio would be much more effective in place of the 50:50 ratio. The 60 being on the final drive stage. Your center to center distance remains the same. The ratio difference in the original design I think is too big and you could have a more practical sprocket reduction (or a greater choice in wheel size) after the gearbox with the new ratio. What do you think?

26-06-2003 23:54

sanddrag

A Few Questions

I've spent countless hours looking into my own personal development of this gearbox. Looking through catalogs, doing calculations, drawings, etc.

Given the game is accomodating, my team is seriously looking into building a drivetrain very similar to that of team 226 next year. To make our life a little easier, I was wondering if you can provide any dimensions on the side plates and bearing hole locations. Do all the shafts' axes of rotation lie in the same plane? Also, I was wondering the length of the side plate spacers. That would be very much appreciated.


A couple more questions:
Is the Chiaphua shaft and the central shaft 3/8 or 1/2 diameter? And how is the Chiaphua shaft attatched to the Chia's armature output shaft: is it pressed, welded or keyed?

27-06-2003 00:19

Andy Baker

Re: A Few Questions

In reference to the TechnoKat tranmission shown in the CAD pic above, I wish that we did have some further reduction in this gearbox. Our main drivetrain mechanical problem this year was AFTER this gearbox, where we had a 11:40 ratio to reduce the speed before driving the tracks. The torque that the 11 tooth gear saw was high and we stripped gears. (however, we had no problems with this gearbox)


Finally, (Kyle is right) I have freed up some time at work and I will be able to do the white paper on this gearbox, which is a dramatic improvement from 2002 gearbox. My goal is to be done with it by IRI (July 18) and have hard copies to hand out at IRI.

Sand... to answer some of your questions:

Yes, all of the axii line in the same plane, with the exception of the drill motor.

The length of the side plate spacers... I need to look at the prints for that one. I think that they are around 1.2".

The CIM motor was keyed to the inside of the 12 tooth gear shaft. This 12 tooth gear was on a 3/8" shaft, a 32 pitch gear was pressed and welded onto the same shaft (mated with a 14 tooth pinion on the drill motor)... and this shaft/gear assembly was broached for an 8mm shaft with a 2mm keyway, mating with the CIM motor.

Andy B.

27-06-2003 01:48

sanddrag

Re: Re: A Few Questions

That's a 12T? On Matt's transmission it appears to be a 16 from this post. Did you both just go little bit different ways there?

27-06-2003 02:17

Andy Baker

Re: Re: Re: A Few Questions

We definitely went different ways. We both started with our design from 2002 (which we put on the internet one year ago)... I made alot of improvements for 2003 for our robot and Matt must've done alot of improvements also.

On that note... if you look at the teams who used our 2002 gearbox, all of them took the published design and improved upon it. Travis Covington of 968 made improvements on it for his team and Paul Copioli of 217 improved it for the Thunderchickens.

Then, there is Paul and Travis of team 48, who put the shifting mechanism as a separate box with just input and output shafts, improving it in a different way.

It was really neat to see what everyone did with this design... how they improved it and made it work for their 'bot. The funny thing about all of this was that none of us talked to each other about it. Travis and I probably compared notes the most, but that was only after he made his design improvements. Paul's job as a designer is to make gearboxes for robot arms, so it's not like he needs advice anyway. Heck, he gave me advice back in 2002 when I was making the first version of this thing.

Andy B.

27-06-2003 10:10

Matt Reiland

Re: Re: Re: A Few Questions

Sanddrag,

What we did in the first stage was make it so that you didn't need any special tools (Such as a broach for the keyway), here is the order we made the first stage (That mounts on the CIM motor) While we could have made things custom, time & money as well as available tools kept us using off the shelf parts.

Step 1:Bought a stock 16 tooth Martin gear.

Problem 1: the bore was larger than the output shaft of the CIM motor.
Solution 1: took a piece of drill rod of the proper size to fit the bore, put a slight knurl on it in the lathe, put a light coat of Green thread lock (essentially high strength epoxy) and pressed it into the gear. When Dry, we bored out the piece of drill rod to slightly under the output shaft of the CIM motor.

Step 2: Made another piece of Drill rod to fit into the new bore on the 16 tooth gear and turned the end down so that it fit the bore of the PIC design 48 tooth gear. We attached them together on this temporary shaft so they were welded together perfectly in line with each other.

Step 3: Take this new assembly of two standard gears welded to each other and turn the hub down on the PIC design gear so that it becomes the end of the shaft and fits in the bearing opposite of the CIM motor.

Step 4: Press the whole assembly onto the CIM motor with more Green LockTite. Advantage: No Setscrews, keyways or anything. Disadvantage: It isn't ever coming off for any reason.

This was how we accomplished the first stage and you can make it easily with only a lathe, welder, and small press.

Next stage of 20 tooth and 50 tooth was simply welding to shaft.

We diverged somewhat from the #45 2002 design but then we left off the Lovejoy coupling and used #25 chain drive to the tank treads (20 tooth/60 tooth) only because lack of planning dictated that we didn't know how the gearbox was going to fit in the chassis and connect up. I would have rather used all gear drive but the chain guides solved our problems. Keep in mind with all the power this had, it never broke a #25 chain. We did however go through 8 Breckoflex belts this year including 4 of the solid center ribbed belts.

I really have to hand it to Team 45 for posting the design so that others could use it either fully or as a great starting point. It is one of those things that advances the community as a whole.

With this much steel, it is imperative that you lighten each and every gear, however having this much weight down low in our chassis is what kept our stacker from falling over like many of the others even though it was over 40" tall.

22-07-2003 21:46

Veselin Kolev

Just interested, how many teams have seen or have costom pressed gears on thier drill motors? By pressed I mean they have taken off the pinion and pressed on another. Because, wouldn't it be really useful if you could press on a 20 pitch gear, and make everything easy?

23-07-2003 06:19

Matt Reiland

It would be somewhat useful, except that even the smallest 20 pitch gear (something like 10 or 12 tooth) is still pretty large and has a standard bore much bigger than the drill output shaft. You would need to press in a drill rod or something into the gear then re-bore it out. Having a larger gear like that would almost certainly also require supporting the output shaft also on the side opposite the motor (Team 45 already does this, we didn't)

23-07-2003 14:23

sanddrag

The smallest 20P I've ever found is a 12T which is still pretty big like Matt said. Having three things pressed together sounds kind of iffy to me. A 32P steel gear works just fine for the relatively small loads being applied right there.

23-07-2003 14:41

Andy Baker

Martin has and 11 tooth 20dp gear and a 10 tooth 20dp spline shaft. We used them both this year.

This was one of our "lessons learned" from 2003: leave yourself enough center distance to vary a wide range of gear ratios after the output shaft of the shifting gearbox.

From the output shaft of our gearbox, we had a coupler, a gear reduction, and then our drive wheel. This gear reduction started out as 2.5:1, but it ended up being 4:1, using a 41 tooth gear (custom) and a 10 tooth gear. I wish we knew we needed a 4:1 when we set the center distances of the gears... they would've been farther apart. This mistake was the cause of many mechanical breakdowns (3 in Pittsburgh and 1 in Chicago).

Andy B.